At present, LCD (Liquid Crystal Display) has been widely used in daily life. It is well known that liquid crystal does not have a light emitting characteristic and therefore it is necessary for the LCD to use a backlight source to implement display. Nowadays, side-type backlight sources prevail for medium/small size display devices.
A side-type backlight source generally comprises a light guide plate and an illuminator which is disposed at a lateral side of the light guide plate. Since the illuminator is typically a linear light source such as a Cold Cathode Fluorescent Light (CCFL), or a spot light source such as a Light-Emitting Diode (LED), the light guide plate is mainly used to convert the linear light source or the spot light source into a surface light source so as to improve luminance uniformity of the backlight source and thus improve displaying effect of the display device.